Dams, culverts and other barriers prevent wild salmon from reaching spawning grounds, causing welfare impacts from exhaustion and failed reproduction with conservation consequences.
Salmon migration barriers cause welfare costs at individual and population level. Individual fish exhausted by repeated failed barrier attempts experience physiological stress, energy depletion and often death before spawning. Salmon that survive to spawn following barrier passage arrive in poorer condition, affecting egg quality and survival. Conservation and welfare align here - restoring free migration benefits both population viability and individual welfare. Fish passage structures can help but must be designed for the specific species and flow conditions to actually be passable. River restoration investment that removes rather than retrofits barriers provides the most reliable welfare and conservation benefit.